1. Technical Field
The disclosure relates to imaging lenses and, particularly, to a compact imaging lens which has fourth lenses, a reduced total length, a wide-angle view and a high brightness.
2. Description of Related Art
In recent years, an image pickup element, such as a CCD (Charge Coupled Device) or a CMOS (Complementary-Metal Oxide Semiconductor) is widely used. In order to obtain small-sized camera modules for use in thin devices, such as mobile phones, personal digital assistant (PDA), or webcams that can still capture quality images, zoom lens systems with high zoom ratio but short overall length are desired.
Factors affecting both the zoom ratio and the overall length of the imaging lens, such as, the number and state of lenses employed, the power distribution of the employed lenses, and the shape of each employed lens, complicates any attempts at increasing zoom ratios but shortening overall lengths of imaging lenses. Additional, when the field of view of the lens is greater than 60°, a number of lens groups must be used to correct aberrations and ensure image quality, which will increase the overall length of the imaging lens. For example, reducing the number of lenses can shorten the overall length of the imaging lens, but zoom ratio and wide-angle view will suffer, conversely, increasing the number of lenses can increase zoom ratio and wide-angle view, but increases overall length of the imaging lens.
Therefore, the demand is high to develop an imaging lens with a short overall length and an reliable optical performance that matches with image sensing chips having enhanced resolution.